Carrot Colours

Photo compliments of USDA Agricultural Research
Service, where researchers have selectively bred carrots with pigments
that reflect almost all colours of the rainbow. More importantly,
though, they are very good for your health. Photo by Stephen Ausmus, USDA.

The individual colours of carrots (except orange) have their own pages select
the colour you wish to know more about.
The coloured carrots are grown the same way as orange ones. They are all basically the same plant. Simply read, understand and follow the instructions on the seed packet.

Many people assume the original carrot colour is orange, when in fact all
the different carrot colours available nowadays come from one common, colourless
ancestor, the wild carrot (Daucus carota). Once domesticated, the former wild
carrot has been subjected to selection that resulted over time in all the
different carrot colours we see today. Red, purple, black, yellow and white are
not only natural carrot colours obtained through artificial selection over the
course of hundreds of years, but also indicators of nutritional diversity and
sources of varied health benefits.

Summary - Some
time about 1,100 years ago farmers living in what is now Afghanistan took
advantage of a mutation in the genes of their white/purple carrots. In the
process of domesticating the white, wild carrot, they discovered a yellow
variant. Six hundred years later, in Europe, cultivation took another turn, and
carrots deepened in hue from yellow to dark orange. The orange carrot probably
existed perhaps as early as the 6th century, and it is likely that it began as a
mutation of the Asian purple carrot and was cultivated, from yellow varieties
into the modern edible plant in the 15th century in the Netherlands. Recent
genetic reserach has proved that orange carrots are derived rom yellow
varieties. Read more here.

NEWS! - Full Carrot Genome sequenced -

Often the evolutionary history of a species can be found
in a fossil record; other times, DNA and genetic fingerprints replace
rocks and imprints. That is the case for the carrot, the richest crop
source of vitamin A in the American diet, whose full genetic code has
recently been
deciphered by a team led by the University of Wisconsin–Madison in
collaboration with the University of California, Davis.

May 2016 - Scientists have unveiled the gene in carrots that gives rise
to carotenoids, a critical source of Vitamin A and the pigment that turns
some fruits and vegetables bright orange or red. The new, high-quality
genome assembly, which the researchers established for an orange
doubled-haploid carrot (Nantes variety), contains more than 32,000
predicted protein-coding genes - more than humans!

As the researchers reported they
were able to track down a candidate gene involved in orange carrot
pigmentation and gained insight into the evolution of plants in the euasterid II lineage, which contains carrots, lettuce, sunflower, celery,
and parsley. Read more here.

Looking back at the plant’s family tree, the researchers have been able to
determine that it split with the grape about 113 million years ago and
from the kiwi about 10 million years after that.

The research team traced
carrot evolution as far back as the dinosaurs. Sometime between the
Cretaceous and Paleogene periods - roughly around the time dinosaurs went
extinct - carrots, along with other plants of the era, picked up genetic
advantages that allowed them to thrive in differing environmental
conditions.

Botanical names - Basically colour alone is
not a reason for taxonomic differences in naming. There is no distinction
between the various colours as far as proper botanical names are
concerned.

Carrots come in two main varieties - Western
(orange/yellow/white) and Eastern (red/ purple/ black) The name for every
Western variety is Daucus carota subspecies sativus. Eastern varieties are
Daucus carota subspecies atrorubens.

The Colour Map: What do we know about the
nutritional value of coloured carrots?

Each pigment has been carefully developed to obtain more attractive
vegetables. At the same time, it resulted in an increased nutritional value.
More exactly, while the vitamins and minerals content (with the exception of
vitamin A), dietary fibre, carbohydrate, protein, fats, sugars profile and
energetic value are more or less the same in all varieties, antioxidant profiles
differ. Different varieties of carrots are a great source of the following
antioxidants:

The colour of yellow, orange and
red carrots is the result of certain carotenoid pigments present in the root.
These carotenoids can be divided into hydrocarbon pigments or
carotenes and oxygenated pigments or xanthophylls.

• Xanthophylls, similar to beta-carotene, give yellow carrots their
golden colours; they are linked to eye health and may reduce the incidence of
lung and other cancers.

• Lycopene, found in red carrots, is a type of carotene also found in
tomatoes. It is believed to help prevent heart disease and, in conjunction with
other phytochemicals, reduce the risk of certain cancers, including prostate
cancer.

• Anthocyanins and pigments of the flavonoid (as opposed to carotenoid)
class are found in purple carrots. In the human body these pigments act as
powerful antioxidants, immobilizing harmful free radicals. Anthocyanins can also
help reduce the risk of heart disease by slowing blood clotting.

• White carrots lack pigment but may contain other beneficial
phytochemicals. More research is needed.

• Lutein is one of the hydroxy carotenoids found in yellow and orange
carrots and makes up the macular pigment of human retinas. Consuming foods high
in lutein may increase the density of this pigment and decrease the risk for
developing macular degeneration and other age-related diseases.

As a simple guide to antioxidant content - the darker the colour, the higher the
antioxidant content. For example, dark orange carrots may have over 80% alpha
and beta-carotene, whilst lighter-coloured orange roots may have less than 40%
pro-vitamin A antioxidants.(Source - Carotenes in typical and
dark orange carrots Philipp W. Simon, and Xenia Y. Wolff J. Agric. Food Chem.,
1987, 35 (6), pp 1017–1022)

This also means that purple-black carrots are richest in antioxidants and, from
this point of view, the healthiest of all colours. They are followed by dark
red, red orange, orange, yellow and white cultivars in roughly this order. All
varieties are high in chlorogenic acid of all antioxidants and contain varying
amounts of other phenolic compounds, notably flavonoids. (Source - Evaluation
of different coloured carrot cultivars on antioxidative capacity based on their
carotenoid and phenolic contents. Grassmann J1, Schnitzler WH, Habegger
R.International Journal of Food Sciences and Nutrition. 2007 Dec;58(8):603-11.)

Overview - The cultivated carrot is believed to originate from Afghanistan before
the 900s, as this area is described as the primary centre of greatest carrot
diversity (Mackevic 1929), Turkey being proposed as a secondary centre of origin
(Banga 1963). The first cultivated carrots exhibited purple or yellow roots.
Carrot cultivation spread to Spain in the 1100s via the Middle East and North
Africa. In Europe, genetic improvement led to a wide variety of cultivars. White
and orange-coloured carrots were first described in Western Europe in the early
1600s (Banga 1963). Concomitantly, the Asiatic carrot was developed from the
Afghan type and a red type appeared in China and India around the 1700s (Laufer
1919; Shinohara 1984). According to this history, it makes sense to envisage
that colour should be considered as a structural factor in carrot germplasm.

Diversity - Carrot varieties contain a wide genetic diversity resulting
in a wide range of size, shape and colour, giving them a wide appeal to
consumers.

Both cultivated and wild carrots
(also known as Queen Anne’s Lace) belong to the same species, Daucus carota,
and are able to interbreed freely. Wild Carrot is native to Eurasia, but
was introduced and considered a weed in the United States. It is a flower often
seen along roadsides whose taproot is a far cry from the carrots usually
served at the dining table. Centuries of breeding have drawn on genetic
diversity hidden in the lowly wild carrot to produce cultivated carrot
varieties of many shapes and sizes.

Domestic carrots belong to the subspecies Daucus carota ssp.
sativus, while wild carrots are a different subspecies, Daucus carota ssp.
carota (Queen Anne’s lace). Cultivated carrots were likely first
domesticated from wild carrots in Central Asia. Traits that evolved during
its domestication include a large taproot with reduced lateral branching
and increased accumulation of carotenoid pigments, which give cultivated
carrots their colour. In contrast, wild carrots have a small, tough, white
root with many branches.

The cultivated carrot contains genetic variation for many traits which
has allowed breeders to produce varieties differing in size, shape and
colour. For example, over time varieties have been developed that have
different levels and types of carotenoids, giving different varieties
either a red, yellow, purple or orange colour. The orange varieties of
carrots most Europeans and Americans know are actually a more recent
development than all other coloured varieties that some growers now
produce for fresh market sales at farmer’s markets. Carrot
varieties with different pigments have slightly different nutritional and
health benefits. Read more below

Recent work will allow breeders to develop carrots with desired traits
much more rapidly. Specifically, geneticists at the University of
Wisconsin and collaborators have sequenced the majority of the carrot
genome, and these and other researchers have developed genetic markers.
This is the first species within this family of plants to have its genome
sequenced. With this information, breeders will have a genetic roadmap to
help them more quickly and accurately select for genes and groups of genes
with desired traits, and then track them in the offspring of crosses as
they select for them. Examples of traits that researchers are examining
include colour and disease and nematode resistance.

Have you ever seen a purple carrot? How about white, yellow, red or black? Most
people haven't, even though such carrots have existed for hundreds of years.
They are available in good health food stores, often called "Rainbow Packs".

Carrots do not have to be orange. As a matter of fact, the orange
carrot is a relative newcomer on the scene. Carrots were originally either
purple or white. Selection and hybridization, probably in the 15th century brought us the
abundant
vitamin A orange carrot we know today.

But carrots are now in the process
of becoming more colourful once again. Today, in both markets and seed
catalogues, you can find not only orange carrots, but red, yellow, white and
purple varieties. With new research that points out the value of the
micronutrients in various vegetable pigments, it is undoubtedly good to eat a
variety of colours of carrots.

It is considered that
Carrots were originally purple or white with a thin root, then a mutant occurred which
removed the purple pigmentation resulting in a new race of yellow carrots. A
tale, probably apocryphal, has it that the orange carrot was specifically bred in the
Netherlands in the seventeenth century to honour William of Orange. Though the
stabilised and domesticated orange carrot does date from around the fifteenth century Netherlands, it is unlikely
that honouring
William of Orange had anything to do with it! Read the full history of
carrot colour here.

The
orange colour did not become popular until the 1500's when
Dutch growers developed the mutant vegetable by selective breeding to make it
less bitter than the yellow varieties, and then it was said to be adopted it as the Royal
vegetable in honour of the House of Orange, the Dutch Royal
Family, although there is no documentary evidence for this latter "fact". The
first carrots were grown for medicinal purposes, perhaps the medicine tasted
good! The main reason
why cooks and housewives preferred orange carrots was because they kept their
colour after cooking and did not leave cookware with an unpleasant colour.

The carotenoid and sugar content of carrots depend on several factors related to
climate and soil as well as genetic determinants. The organoleptic (taste)
qualities of carrots are controlled by a balance between a range of compounds
including both reducing and non-reducing sugars.

Research at the Universities of Krakow (Poland) and Warwick (UK) confirms
what previous studies have shown, that there are no clear differences detected
in total sugars related to root colour. Carrot sweetness depends on the presence
of sucrose and the two reducing sugars glucose and fructose. Sugar content is a
quantitative trait under polygenic control with heritability estimated by other
authors at 0.45. The ratio of non-reducing to reducing sugars in carrot roots is
determined by a single gene. Volatile compounds additionally influence the
perception of sweetness in carrots. Terpenoids like terpinolene, terpinene or
caryophyllene, are indicated as important components. The presence of soluble
phenolics also highly correlates with sweetness as demonstrated for processed
carrots.

European/American material do however tend to have more sugar than
Asiatic types. This because of cultural taste.

In simple terms, taste is a quality influenced by other compounds as well as
sugar. Carrots of the various colours contain approximately the same amount of
sugar and it is other compounds which determine whether one coloured carrot is
sweeter than another colour.

Sugars accumulate in the root during photosynthesis and act as a reserve to
support that biennial phase of the plant, unless we harvest the carrots and eat
them first! There is very little starch in carrots compared to potatoes, for
example, so storage carbohydrates are primarily glucose, fructose and sucrose.
Other root carbohydrates are tied up in the cell wall as pectins, cellulose and
lignin, and once sugars get incorporated into the cell wall they are not able to
be released for use by the plant again (like starch, which can be degraded).

There are definite wide differences in sugar content, 5-fold is not uncommon
(depending what's being compared). One major gene controls what type of sugar is
stored: either predominantly glucose + fructose (which is typical) or
predominantly sucrose (which is not common).

These wide differences can be associated with colour, but that's by chance,
not cause and effect. Breeders can however breed for sugar type
(glucose-fructose or sucrose) and amount (higher or lower) in any colour class.
(Source P W Simon, USDA).

Research at the University of Wisconsin-Madison suggests that pigments in these
colourful carrots, which taste just like regular carrots, may help prevent heart
disease and cancer, and reduce cholesterol. Studies examining the health
benefits of fruits and vegetables are revealing the disease-preventive powers of
the pigments that give plants their distinctive colours. (image below,
compliments of Pelosi, A carrot farm in Tuscany -
website
here)

Orange carrots get their colour from beta carotene, a pigment the body converts
to vitamin A. Vitamin A deficiency, although rare in the United States, poses
a major public health problem in developing countries second only to protein
malnutrition.

According to the World Health Organization, vitamin A deficiency partially
or totally blinds nearly 350,000 children from more than 75 countries every
year. Roughly 60 percent of these children die within months of going blind.
However, vitamin A deficiency is preventable.

The colour orange stimulates the appetite - read more about the colour of
adventure and social communication, and empower yourself with colour psychology
here.

Why are orange carrots, the colour orange? -
it's the Beta Carotene - Carrots
are orange because they absorb certain wavelengths of light more efficiently
than others. Beta-carotene is the main pigment and is mainly absorbs in the
400-500nm region of the visible spectrum with a peak absorption at about 450nm. Carotenoids are one of the most important groups of natural pigments. They cause
the yellow/orange colours of many fruit and vegetables. Though beta-carotene is
most abundant in carrots it is also found in pumpkins, apricots and nectarines.
Dark green vegetables such as spinach and broccoli are another good source. In
these the orange colour is masked by the green colour of chlorophyll. This can
be seen in leaves; in autumn, when the leaves die, the chlorophyll breaks down,
and the yellow/red colours of the more stable carotenoids can be seen.

Colour of the carrot is due to the presence of pigment. The orange colour is due to
carotenes and yellow due to anthyocyanin. The variation colour is due to
accumulation of carotenoids in varying degree. The colour development depends on
cultivar, growing season and age of the root. A temperature of1.5 to 21.1 0 c is
best for colour development. Wet weather proceeding to harvesting results in low
carotene. Carotene synthesis is more in bright sunshine

The main variation in the colour of carrot is due to genotype, the development
of the plant, the temperature during the growing season and also other agronomic
practices such as the use of fertilisers. (reference Bajaj et
al 1980, Van de Burg et 2000 - Plant food Human Nutrition 30: 97-107; Journal of
Food Science and Agric 80:880-912)
(photo right Harlequin variety, available from DT Browns, UK)

Carrot (Daucus carota) is a biennial plant that accumulates massive amounts of carotenoid pigments in the storage root. Although the root of carrot plants was
white before domestication, intensive breeding generated the currently known
carotenoid-rich varieties, including the widely popular orange carrots that
accumulate very high levels of the pro-vitamin A carotenoids b-carotene and, to
a lower extent, a-carotene. Recent studies have shown that the developmental
program responsible for the accumulation of these health-promoting carotenes in
underground roots can be completely altered when roots are exposed to light.
Illuminated root sections do not enlarge as much as dark-grown roots, and they
contain chloroplasts with high levels of lutein instead of the b-carotene-rich
chromoplasts found in underground roots. Analysis of carotenoid gene expression
in roots either exposed or not to light has contributed to better understand the
contribution of developmental and environmental cues to the root carotenoid
profile.

Young carrot roots are pale but after the first month of growth they start
accumulating carotenoids to reach highest levels in about 3 months, just before
secondary growth is completed. It is likely that wild carrot plants had
uncoloured roots of a bitter taste and a woody core but were initially cultivated
because of their aromatic leaves and seeds which were thought to have medicinal
properties. Carrot domestication probably took
place around the 10th century but despite intensive breeding procedures
since the 19th century, the background structure coming from demographic and
early cultivation history still persists in currently cultivated carrot germplasm. At present, carrots (i.e. mature D. carota roots) are available
in a range of colours, although orange varieties are most popular because of
cultural acceptance. Even though
the high carotene content in carrots makes them one of the richest pro-vitamin A
sources in the human diet, the mechanisms regulating their production remained
poorly known until recently. (ref - Biosynthesis of
carotenoids in carrot: An underground story comes to light Manuel Rodriguez-Concepcion,,
Claudia Stange - Archives of Biochemistry and Biophysics 539 (2013) 110–116)

Important Note - The chemical constituents of carrot are not
there by chance, but perform a function. Many constituents of the orange
carrot we now cultivate are also in the white root of the wild carrot,
Queen Anne's lace, from which our carrot was developed. This is true of
falcarinol, falcarindiol, and myristicin. Carotene (present in small
amounts in Queen Anne's lace) has been increased by centuries of
selection. Volatile oils have been decreased in this process. Plant
scientists must continue to monitor all known constituents nutritive and
non-nutritive - as new cultivars of the carrot are developed to keep our
vegetables nutritious and safe. Plant breeding for the sake of high
yields, appearance, and keeping quality will not be sufficient.

Carotenoid pigments provide red, yellow and orange colours
and antioxidant protection to a wide variety of plants, animals, bacteria, and
fungi. In plants, carotenoids play a protective role in photosynthesis by
dissipating excess light energy absorbed by the photosynthetic mechanism.

What it means is that carotenoids are good antioxidant
compounds which effectively prevent damage to DNA or other important parts of
cells. This damage can be caused by ‘free radicals’ which are very reactive
molecules generated through the normal living processes of a cell (the release
or generation of energy).

In plants, the carotenoids protect the plant cells from
damage caused by energy from the sun in the same way. Carotenoids are also a
starting point for the construction of other useful compounds, so their function
is not always protective. There are possibly more important parts of the
plant containing carotenoids (eg the leaves) where they are less obvious because
they are masked by the green colour of chlorophyll. In the parts of the plant
which don’t photosynthesize, we can see their presence more easily.

The Unique Properties of all the Colours -

The colour of carrot root is the result of various pigments that serve as
intermediate products in the carotenoids pathway (Koch and Goldman 2005). Six
carotenes have been reported in carrots, as α-, β-, γ- and ξ-carotenes, lycopene
and β-zeacarotene (Simon and Wolff 1987). The major pigments responsible for
orange and yellow colour of the roots are α- and β-carotene. β-carotene often
represent 50% or more of the total carotenoids content. The red colour of the
carrot root is caused by lycopene and the yellow colour is affected by
xanthophylls (Rubatzky et al. 1999). White roots are low in total carotenoids
(Buishand
and Gableman 1979). Purple carrots contain very high contents of phenolics,
mainly anthocyanins, and are characterized by a higher antioxidant capacity than
orange, yellow or white varieties (Alasalvar et al. 2005). Differences in
chemical composition, mainly among the phenolics, have been demonstrated as
useful in distinguishing some Daucus species, whereas polyacetylenes, coumarins
and sugars have not provided useful distinction (Crowden et al.1969).

Each unique colour of carrots has different pigments and health benefits.
Coloured carrots are becoming popular again and it is hoped that their colourful
appearance will entice young children (and adults!) to eat a more balanced diet
and reap the health rewards from these vegetables. Studies have been carried out in the USA on the differing properties of different
coloured carrots.

Different carrot colours nutrition. Each pigment has been
carefully developed to obtain more attractive vegetables. At the same
time, it resulted in an increased nutritional value. More exactly, while
the vitamins and minerals content (with the exception of vitamin A),
dietary fiber, carbohydrate, protein, fats, sugars profile and energetic
value are more or less the same in all varieties, antioxidant profiles
differ. Different varieties of carrots are a great source of different
types of antioxidants:

Orange Carrotshighest in beta-carotene, contain smaller amounts of
alpha-carotene, gamma-carotene, lutein, zeaxanthin. The carotenes are both
orange pigments. High in Vitamin A essential for well-being, healthy eyes.
These carrots originate from Europe and the Middle East. Like all carrots
these are a good source of fibre, which is vital for healthy
gastrointestinal tracts and is linked to reducing cholesterol. Their
pre-dominant pigment is beta-carotene; the orange pigment which is
converted by the liver to vitamin A which is important for healthy vision.
It forms rhodopsin, which the eye needs to see in dim light. This is
accomplished by raising the effectiveness of the light sensitive area of
the retina. Vitamin A also maintains the surface linings of the
respiratory, urinary, and intestinal tracts, and regulates the immune
system by helping white blood cells fight infections.

Yellow carrots contain xanthophylls and
lutein, pigments
similar to beta carotene, which help develop healthy eyes aid in the fight
against macular degeneration and may prevent lung and other cancers
and reduce the risk of astherosclerosis (hardening of the arteries).
These came from the Middle East. The major pigment found in the yellow
carrots is xanthophyll which helps develop healthy eyes. Studies have
shown that intake of xanthophyll-rich foods are associated with a
significant reduction in the risk for cataract (up to 20%) and for
age-related macular degeneration (up to 40%) (Moeller, Jacques &
Blumberg 2000). Yellow Carrot page.

Red carrots highest in lycopene(another form
of carotene), they also contain smaller amounts of lutein, beta-carotene,
alpha-carotene. are tinted by lycopene, a pigment also found in tomatoes and watermelon; lycopene is
associated with the reduced risk of macular degeneration, serum lipid
oxidation, helps prevent heart disease and a wide variety of cancers including prostate cancer. Originally
from India and China. Red carrots contain the pigment known as lycopene
which has been associated with a lowered risk of prostate cancer in men
and heart disease. It also helps maintain healthy skin. Red Carrot page

White carrots lack any pigmentation, but do contain
other health-promoting substances called phytochemicals, natural bioactive
compounds found in plant foods that work with nutrients and dietary fibre
to protect against disease. One might say these
are the least healthy of carrots. They originate from Afghanistan, Iran,
Pakistan. These chemicals may be important in reducing the risk of
atherosclerosis , which is the build up of fatty deposits in artery walls.
White carrots are preferably used in baby foods to prevent them from
forming orange skin. White carrot page

Purple carrots highest in anthocyanins, also
contain beta-carotene and alpha-carotene and small amounts of lutein and
zeaxanthin. They get
their pigment from an entirely different class, the anthocyanins, these pigments
act as powerful antioxidants that protect key cell components, grabbing and holding on to harmful free radicals
in the body. Anthocyanins also help prevent heart disease by slowing blood
clotting and are good anti inflammatory agents. These originate from
Turkey, and the Middle and Far East.

The Purple Haze variety have a more purple/red and white centre.
Purple carrots neutralize the damaging effects of free radicals which
disrupt the structure of other molecules leading to cellular damage,
aging, and various health problems. Anti-inflammatory properties of
anthocyanins have also been observed. They neutralize enzymes that destroy
connective tissue and they repair damaged proteins in blood vessel walls.
Finally, anthocyanins may prevent heart disease by slowing blood clotting
and inhibiting the absorption of LDL, “the bad cholesterol.”

Black Carrotscontain anthocyanins, part of the flavonoid family with antioxidant
properties. Flavonoids are currently under investigation as anticancer
compounds, as free radical scavengers in living systems, as well as
inhibitors of LDL (the bad) cholesterol and the black carrot anthocyanins
are especially active.

The Black variety has anti-bacterial and anti-fungicidal
properties and oil made from its seed can help control scalp itchiness and
provides essential nutrients for hair growth. The ancient black carrot has
been making a comeback, not so much for culinary purposes but as a source of
natural food colorants.
These originate from Turkey, and the Middle and Far East. Black carrot page

See more colour variations
here
(new window) - University of Agriculture, Krakow.